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https://blitiri.com.ar/repos/chasquid
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c12fa0eed7
This patch adds a new internal/safeio package, which is meant to implement safer version of some I/O related functions. For now, only an atomic version of ioutil.WriteFile is implemented. More may be added later if there's a need for them.
44 lines
1.1 KiB
Go
44 lines
1.1 KiB
Go
// Package safeio implements convenient I/O routines that provide additional
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// levels of safety in the presence of unexpected failures.
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package safeio
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import (
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"io/ioutil"
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"os"
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"path"
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)
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// WriteFile writes data to a file named by filename, atomically.
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// It's a wrapper to ioutil.WriteFile, but provides atomicity (and increased
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// safety) by writing to a temporary file and renaming it at the end.
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//
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// Note this relies on same-directory Rename being atomic, which holds in most
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// reasonably modern filesystems.
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func WriteFile(filename string, data []byte, perm os.FileMode) error {
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// Note we create the temporary file in the same directory, otherwise we
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// would have no expectation of Rename being atomic.
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tmpf, err := ioutil.TempFile(path.Dir(filename), path.Base(filename))
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if err != nil {
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return err
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}
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if err = os.Chmod(tmpf.Name(), perm); err != nil {
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tmpf.Close()
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os.Remove(tmpf.Name())
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return err
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}
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if _, err = tmpf.Write(data); err != nil {
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tmpf.Close()
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os.Remove(tmpf.Name())
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return err
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}
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if err = tmpf.Close(); err != nil {
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os.Remove(tmpf.Name())
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return err
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}
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return os.Rename(tmpf.Name(), filename)
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}
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